Method of inhibiting gum formation in naphthas and products obtained thereby



Patented Feb. 25, 1936 UNITED STATES PATENT OFFICE METHOD OF INHIBITING GUM FORMATION IN NAPHTHAS AND'PRODUCTS OBTAINED 'I'HEREBY Delaware No Drawing. Application April 24, 1931, Serial No. 532,706

11 Claims.

The present invention relates to a. method of inhibiting or retarding gum formation in low boiling hydrocarbon oils and will be fully understood from the following description:

Naphthas containing large quantities of gum or constituents tending to form gum during storage or in sunlight are objectionable for many purposes, such as motor fuels, light solvents, etc. Recently a careful study of gum formation has been made by chemists and several organic compounds have been found which, when added in small quantities to low boiling hydrocarbon oils, will retard or inhibit gum formation for periods of time varying with the nature of the compound, the'oii and other conditions. U. S. application Serial No. 497,334, of Carlos L. Gutzeit filed November 21, 1930, proposes the use of dyes, such as indo-phencls and oxaziner, indamine-,

' eurhodine-, safranine-, apo-safranine and amino azo-bases which lose their color before'losing their inhibiting power.

The present inventionrelates to an improvement of the process described in the application cited.

When a dye is used alone as gum inhibitor, the concentration required to inhibit gum formation in storage is usually around one part by weight of dye in 10,000 or 20,000 parts of naphthe. Withmost dyes, however, the proper color of the dyed gasoline can be obtained in concentrations as low as one part of dye in 100,000 or in 200,000 parts of naphtha. One aspect of the present invention relates to. the addition to naphthe. of a dye gum inhibitor in concentration insuilicient to provide effective gum inhibition together with a substantially colorless gum. inhibitor to prevent gum formation during storage in the absence of sunlight. The expression effective gum inhibition is meant to designate the protection of the naphtha against gum formation on six months storage in the absence of sunlight. Such a combination of a dye and a colorless gum inhibitor will provide effective gum inhibition during storage and the extremely small quantity of dye will insure all the benefits which can be obtained from using a dye alone as gum inhibitor. The dye in such a combination serves as an indicator inasmuch as the color of the naphtha containing the combined gum inhibitor will fade before the inhibition power ceases. Examples of colorless gum inhibitors which may be added to gasoline in conjunction with a minute quantity of dye inhibitor are the following: alpha naphthol, secondary amyl para-amino phenol, hexyl para-phenylene diamine, etc. The

following examples will serve to illustrate naphthas stabilized against gum formation in storage by the combined gum inhibitors above described.

'Per cent The blue dye obtained by the condensation of a naphthol with para-nitroso dimethy] aniline Alpha naphthol Gasoline Both of these dyes belong to the indophenols.

The colorless gum inhibitors used in the above combination will prevent gum formation on long standing in storage in the absence of sunlight; they will, however, change when exposed to sunlight. Thus, for example, alpha naphthol turns blue in sunlight and could not be used with great efliciency to prevent gum formation in gasolines which are exposed to sunlight.

The second aspect of the present invention, relates to the addition to naphtha of a combined dye inhibitor and colorless inhibitor, the latter being a light stable colorless inhibitor, such as for example, aniline, phenol and other vhomologues and derivatives, ortho-, meta-, and paracresol, etc. The colorless inhibitor in this case will protect the dye against fading in the sunlight as long as the-combined inhibitor is able to effectively prevent gum formation in the gasoline. In some cases the colorless inhibitor used is a comparatively poor inhibitor in itself, for example, aniline or phenol, but in combination with a powerful dye inhibitor it will have the effect of protecting the dye inhibitor against fading in the sunlight. The dye inhibitor in this case is added in an amount sufficient not only to color the naphtha but also to prevent gum formation therein. The expression light stable colorless inhibitor is meant to designate a gum inhibitor whose solution in gasoline will not discolor noticeably to the naked eye when exposed for 4 hours to strong sunlight in a 4 ounce glass bottle. The preferred concentrations of the constituents of the combined inhibitor are the following: dye

0.0024101 per cent, colorless inhibitor 0.01-0.05

per cent by weight of the naphtha. The percentages may vary but the total amount of the combined gum inhibitor 1s usually below 0.1 per cent.

The following examples will be given for the.

purpose of illustration:

. Per cent The blue die obtained by the condensation 'of alpha naphthol with para-nitroso dimethyl aniline 0.005 Mono methyl aniline 0.020 Naphtha 99.975

, Percent The red dye obtained by the condensation of diphenyl amine with para-nitroso phenol 0.003 Tricresol 0.020 Gasoline 99.977

In both modifications of our process the amount of the combined gum inhibitor is very small and is usually less than 0.1 per cent by I claim is:

further stabilize tion. p v

2. Motor fuel according to claim-1, in which weight of the naphtha. The combined gum inhibitor is in general sufficiently oil soluble and may be readily distributed uniformly throughout', even large bodies of oil by simple mixing means. If desirable they may be dissolved in benzene or other suitable solvent.

Havingthus described our invention what we .1. A motor fuel comprising cracked hydrocarbon spirits of the type. normally tending to form gum containing a colorless guminhibitor selected from aromatic amino and phenolic compounds in quantity sufllcient to inhibitgum formation, and a dye selected from the group consisting of indophenols and oxazine-, indamine-, eurhodine-, safranine-, and aposafranine bases in quantity suflicient to impart color to the fuel and the gasoline against gum forma- 7. A composition of matter comprising gasoline 99.977% approximately, tricresol 0.020% approximately, and the red dye obtained by the condensation of diphenylamine with paranitroso phenol 0.003% approximately, said dye and tricresol both having gum inhibiting power, and the tricresol tending to prevent the fadingof the dye- 8. A motor fuel comprising cracked hydrocarbon spirits of the type normally tending to form gum containing a colorless gum inhibitor selected from aromatic aminoand phenolic compounds in quantity sumcient to inhibit gum formation and an indophenol dye in quantity 'sufllcient to impart color to the fuel and further'stabilize the gasoline against gum formation.

-9. Process for inhibiting gum formation in cracked gasoline, which comprises adding to the gasoline aminute amount of' a dye inhibitor to color the gasoline to the desired extent and protect the same partly against the formation of gum, said dye being selected from the class consisting of indophenols and oxazine-, indamine-, eurhodine-, safranine., and aposafranine bases, and also adding to the gasoline a small quantity of a colorless gum inhibitor selected from the class consisting of aromaticv amines and phenolic compounds.

10. Process for inhibiting gum formation in cracked gasoline and stabilizing. an inhibitor dye contained therein and selected from the group consisting of indophenols and oxazine-, indamine-, eurhodine-, safranine-, and aposafraninebases, which comprises adding thereto a small amount of a colorless gum inhibitor selected from the class consisting of aromatic amines and-phenolic compounds.

11. Process for inhibiting gum formation in cracked hydrocarbon spirits of the type normally tending to form gum. which comprises adding to said spirits a colorless gum inhibitor selected from aromatic amino and phenolic compounds in quantity sufficient to inhibit gum formation and an indophenol dye in quantity 'sufiicient to impartcolor to the fuel and fln'ther stabilize the gasoline against gum formation.

IEONARD E. sARGEN'r. CARL wmme. JAMES F. DUDLEY. 

